This invention relates to releasable suspension of an airborne store on a carrier aircraft and to a store for releasable suspension on a carrier aircraft.
Conventional airborne store suspension and release equipment will be poorly suited to use on fast military aircraft in the future due to inevitable problems of aerodynamic drag caused by gaps, apertures and excrescences that are unavoidable features of the design of the equipment. Further, the equipment that incorporates rails for launching stores from an aircraft on release is very different from that used for release of suspended free-fall stores from an aircraft and creates significant parasitic drag.
U.S. Pat. No. 4,392,411; WO89/12210; EP-A-0,296,010 and its equivalent U.S. Pat. No. 4,870,885; WO93/03321; EP-A-0,759,532; GB-A-2,309,069 and U.S. Pat. No. 5,970,842 each disclose examples of xe2x80x9cTeexe2x80x9d hangers for use in such rail launch equipment. In each case the xe2x80x9cTeexe2x80x9d hangers are bulky and present a complex profile to the airstream in flight. U.S. Pat. No. 4,392,411 submits that difficulties arise if the hanger (there are usually three, one behind another along the length of the store) remains on the store after release of the store from the aircraft. These are difficulties which affect the weight of the store, air drag caused by the hanger or parts thereof in the airstream and the space required to accommodate such hangers where they are sunk into structure of the store. Accordingly the hangers are arranged to be separated from the store so that they remain in the embracing means that are mounted in the structure of the store carrying aircraft. This requires a complicated arrangement for mounting each of the hangers on the store and for separating each of those hangers from the store at launch so that they remain in the aircraft structure.
If store suspension and release equipment for a free-fall airborne store should include a U-shaped lug which is secured at the ends of its limbs to the store and which is adapted to be engaged by a hook which is pivotally mounted in the aircraft structure and arranged to pass through the aperture that is formed between the store and the base of the lug between the limbs thereof so as to secure the store to the aircraft and bracing arms are provided which extend over the surface of the store in opposite directions from the lug to which they are joined, the store is able to move excessively relative to the aircraft structure during aircraft manoeuvring due to low structural stiffness of the equipment. EP-A-0,062,581 and its equivalent U.S. Pat. No. 4,416,437; EP-A-0,144,265 and its equivalent U.S. Pat. No. 4,632,338; and JP-A-6241694 disclose examples of such store suspension and release equipment. Even if each bracing arm is provided with a manually adjustable bracing screw which is screwed through it at a location spaced from the lug, each screw being manually adjustable so as to be put in compression with a head portion thereof engaged with the store surface, this arrangement would require considerable preloading of the sway brace arms to ameliorate the inherent lack of stiffness and prevent undesirable store rattle. The load path from the store to the aircraft structure would involve several bending beam elements which would distort excessively under load. EP-A-0,143,713 and its equivalent U.S. Pat. No. 4,620,680 disclose a complicated arrangement in which the hooks may be raised during loading so as to be set under the bracing arms which are initially set at their highest position and which, by operation of a complicated assembly of springs and stops, then automatically positions the bracings arms at different levels depending on the diameter of the store that has been hooked on. EP-A-0,745,531 discloses the provision, in an aircraft which is formed with different housings from which different sizes of store are hung by such a hook suspension, of a device which is fitted into one of the housings that is not used for suspending the store that is hooked on. The device that is so fitted into the one housing has a finger which projects into a hole provided in the store that is hooked on for the purpose of holding the store in place in terms of yaw.
An object of this invention is to enable releasable suspension of an airborne store on a carrier aircraft by means having a significant structural stiffness so that, during aircraft manoeuvring, roll of the store relative to the aircraft structure from which it is suspended is minimal. Another object of the invention is to minimise the effect of parasitic drag on the store due to means provided thereon for the releasable suspension. A further object of the invention is to provide means for fitting to a store for releasable suspension from a carrier aircraft that are suitable for both free-fall stores and rail launched stores.
According to one aspect of this invention there is provided an airborne store suspension and release arrangement including one hanger having a narrow strut portion and an enlarged cross-section portion, the narrow strut portion being adapted to be mounted by one end on a store so as to be upstanding therefrom and the enlarged cross section portion being at another end of the strut portion, the arrangement also including means adapted to be mounted in structure of a store carrying aircraft and operable to embrace said hanger by embracing the enlarged cross section thereof whereby to retain the store suspended from the aircraft and means operable to effect release of the store from the embracing means in order to release the store from the aircraft, wherein means separate from said hanger are provided which are operable in combination with said hanger to establish a couple in reaction to a rolling moment to which said store is subjected during manoeuvring of said store carrying aircraft when said hanger is mounted on said store and said store is suspended from said aircraft structure, the enlarged cross section portion of said hanger being embraced by said releasable embracing means.
The provision of means separate from said one hanger, or, in such an airborne store suspension and release arrangement which includes more than one such a hanger, of means separate from each said hanger which are operable in combination with the respective hanger to establish a couple in reaction to a rolling moment to which said store is subjected during manoeuvring of said store carrying aircraft when the respective hanger is mounted on said store and said store is suspended from said aircraft structure, the enlarged cross section portion of the or each said hanger being embraced by the respective releasable embracing means, enables use of such a hanger which is much more slender than the xe2x80x9cTeexe2x80x9d hangers known in the art and which presents a smaller and simpler profile to the airstream than the xe2x80x9cTeexe2x80x9d hangers known in the art do.
In one embodiment, said store and said aircraft structure are formed with surfaces which abut one another when said store is suspended from said aircraft structure, said means operable in co-operation with said one hanger to establish said couple including said abutting surfaces. The upstanding portion of said one hanger is aligned with the geometrical center of said store in said one embodiment.
In another embodiment there are two said hangers and respective releasable embracing means operable to embrace the enlarged cross section portion of each hanger, the two hangers being located one on either side of a vertical plane through the center of the store, the vertical plane being substantially midway between the upstanding strut portions of the two hangers. The releasable embracing means may be releasable clamping means operable to clamp said enlarged cross section portion of said one hanger. Alternatively, the embracing means may be overhead rail means from which said store is adapted to be suspended and on which said enlarged cross section portion of each said hanger is adapted to slide.
According to another aspect of this invention there is provided an airborne store fitted with one hanger having a narrow strut portion and an enlarged cross-section portion, the narrow strut portion being mounted by one end on the store so as to be upstanding therefrom and the enlarged cross section portion being at another end of the strut portion remote from the remainder of the store on which it is mounted and being adapted to be embraced by embracing means mounted on a store carrying aircraft whereby to retain the airborne store suspended from the aircraft, and means separate from said one hanger which are adapted to interact with corresponding means provided on the store carrying aircraft when the airborne store is suspended therefrom whereby to establish a couple in reaction to a rolling moment to which said store is subjected during manoeuvring of the store carrying aircraft.
According to further aspect of this invention there is provided an adaptor plate which is adapted to be fitted to an arcuate surface of a store and which has a generally flat surface for engagement with a co-operating flat surface formed on a carrier aircraft, the adapter plate being provided with at least one hanger having a narrow strut portion and an enlarged cross-section portion, the narrow strut portion being mounted by one end on the flat surface of the adapter plate so as to be upstanding therefrom, the enlarged cross section portion being at another end of the strut portion and being adapted to be embraced by embracing means mounted on a store carrying aircraft whereby to retain a store suspended from the aircraft when the adapter plate is fitted to that store.